It is well-known in the art to produce coal tar/epoxy compositions for coating, insulation, encapsulation and similar uses. Such compositions typically include 20% or more of volatile solvents and diluents to maintain a low viscosity for spray applications and for good compatibility between the coal tar and epoxy components. It is also well-known in the art to employ amine curing agents for hardening such coal tar/epoxy compositions.
The need for volatile solvents in such compositions in the past has greatly limited their applications as well as detracted from the overall quality of the resulting coatings. Thus, because of the intermediate need for flammable solvents which are difficult to completely drive-off from the final product, coal tar/epoxy compositions have had limited use in some electrical encapsulation and certain coating applications. Also, the process of driving-off the volatile solvents during curing often results in blistering of coatings, non-uniformity and inferior adhesion properties. Moreover, the need for volatile solvents and diluents reduces the concentrations of reaction ingredients during the curing phase and results in a coating of inferior hardness, water-resistance and impact strength. Furthermore, government regulations have increasingly restricted the amount and nature of volatile solvents which may be discharged into the atmosphere. One approach to this problem used in the past was to employ reactive solvents and diluents. These materials, however, are prohibitively expensive and still present certain problems. Accordingly, it has long been desired to formulate coal tar/epoxy compositions having viscosities less than about 1000 cps. at ambient conditions without the use of volatile solvents.